This Means War
by ennife
Summary: Casey and the new girl on the block fight it out for Derek's attention. One is his exact opposite, and the other is his perfect match. Who will win his heart?
1. Chapter 1

_I don't own Life with Derek._

* * *

"Are you coming to the party tonight?" My _'new best friend'_ Mercedes asked, struggling to complete her sentence while she chewed. It was late, and we had just left the food market a few blocks down from our house, bags of junk food in our hands. Apparently, she couldn't wait to get home to consume her twinkie.

"At your place?" She asked, a small, girly burp escaping her lips as she finished speaking. She giggled, "You sure you want me there?"

I forced a fake smile. "Yeah! Of course! Why wouldn't I?"

"Because five minutes ago you were yelling at me, telling me to act more mature." Mercedes kept her soft grin plastered to her face.

I paused as we walked along the side of the road, cars passing by quickly. "Well, yeah ..." I hesitated, " ... just ... try not to do anything moronic."

"Oh, so now I'm a _moron_? Because -"

"No, no, no! That's not what I meant! That came out so wrong -"

"Jesus, Casey, chill!" Mercedes held up her hands as a sign for me to stop having my slight panic attack. "It's okay, really. I know what you meant. Act responsible, no burping, no stuffing my face, no jokes, no having fun."

"And no doing anything Derek would do ...." I said, knowing that phrase would basically cover all the rules.

Mercedes laughed, "Don't worry! I'm not exactly into picking up random girls. The dudes are more my type."

"Yeah, me too," I forcefully giggled, not really knowing what else to say. After all, _I_ wasn't hanging out with _her _by choice. _She_ was hanging out with _me_.

"So, I'm assuming Derek will be there?" Mercedes asked, her question confusing me.

"Well, yeah, I think so." I paused, trying to remember if today was the day Derek and Sam were going to the concert by the mall. "Why do you ask?"

"Hey, if I'm not allowed to get this party started, someone has too." Mercedes began swifting through the plastic bag she was carrying, pulling out a bag of skittles.

I was starting to get aggravated. "No, no, no. No 'getting this party started'! This is the first party my parents are letting me throw while they're away. I'm not going to let Derek - _or you - _ruin it!"

"Shesh, Casey, it's called being sarcastic." Mercedes everlasting smile faded. "You met me three days ago. How do you know that I can't behave myself when told?"

_Because the manager of the food market told you to 'shut up' several times, and you continued to hop around the ailes like a crying baby? _I thought. My reply varied, "Yeah, you're right, I guess. I'm sorry."

Mercedes popped a lime green skittle into her mouth. "It's 'mmkay."

"Well, isn't this your house?" I asked, praying that she said yes.

"No, mine is the next one up." She said, pointing towards the medium sized, brick house a few yards in front of us. The house looked almost exactly like ours, only the door was painted a deep, navy blue. Mercedes took a skip forward like an excited child. She giggled, "Wanna come inside? Get a soda?"

"Uh, no. I ... don't like soda. Besides, I've -"

"You don't have to have soda - we've got water, some of that damnly gross veggie juice, milk -"

"No really, Mercedes," I hurried. "It's fine. I've got a lot of work to do at home, anyway. The party's in three hours and I'm not anywhere near ready," I lied. My house had been set up since this morning.

"Oh, 'kay. That's cool. What time do I need to be over?"

"Around seven ..."

"Okay!" Mercedes began walking up her driveway backwards, still facing Casey. "See you then?"

"Yeah, sure," I said in a fake, happy tone. I let out a loud sigh as soon as she closed her door.

* * *

**The Score:**

**Casey: 0 Mercedes: 0**


	2. Chapter 2

_I don't own life with Derek. Sorry for the many spelling errors in the last chapter._

* * *

**_Mercedes' Point of View_**

I stood in front of my bedroom mirror, brushing my long, dark, chocolate brown hair. I had tried to straighten it, but it was already starting to go back to its normal wavy texture. It's not that I didn't like the way it looked, but it was about time for a change. I had the same old beach waves everyday. Maybe my mom was right .... It _was _time to invest in some hair product. _Weird._

I didn't have anything special on. Just my lime green soccer tee-shirt from last season, a pair of skinny jeans (not too tight), some converses, and some eyeliner and mascara. Just my normal.

I sighed, finally giving up the fight with my hair. I decided my best option was a ponytail, with my sidebangs left down, and a pink bandana folded to look like a headband. Once I was done with my 'new do', I looked in the mirror and shrugged .... It was _okay_. A little frizzy and carefree, but in a good way ... kind of.

* * *

Twenty minutes later, I was standing out front of Casey's house. The location of the par-_tay. _I had to make this good. Max had given me fifty bucks to crash this thing, and I sure as _hell_ was going to live up to my promise. Besides, I had a chance to destroy _Casey McDonald, the girl that _crushed _Max. _After all, he was my cousin. Family hasta' stick with family.

Slowly, I reached out and pushed the doorbell. She opened the door in seconds.

"Mercedes!" Casey exclaimed, a hint of disappointment in her tone. I didn't care.

"This the right place?" I asked jokingly, doing a cheesy little 'hello there' wave.

"Yep, come in," She said, her smile big and bright. I almost burst out laughing at how fake it was.

"So ... ehhmmm ..." I paused, " you got food?"

Casey shut the door with a slam, looking a little stiff and awkward. "Uh, yeah, in the kitchen. Don't spill anything? Please?"

"No problemo, Commander Casey," I giggled, launching myself towards the kitchen.

Her house was nice, I had to admit. But the kitchen was ... too perfect. It was everything I expected out of a place _she_ lived in. _God, imagine what her _family_ is like. _That thought sent shivers up my spine. The thought of a family of control freaks scared the shit out of me.

I spotted a bowl of chips sitting on the counter, and I couldn't help but many take a few. I was just sitting there, savoring their salty flavor, when I heard a voice from behind.

"And _you_ are?"

I turned around, finding myself face to face with a pair of mud brown eyes. It was Derek, the boy Casey complained about constantly. I had known the girl for three days, and she had mentioned him twenty or so times. Trust me, I had been counting. I smiled my goofy smile, "Mer-ce-des! Just moved here," I said, stuffing another chip into my mouth after I finished. Hey, I couldn't help myself.

Derek seemed skeptic. "You don't seem like someone Casey would invite to one of her 'parties'," he folded his arms.

"Yeah, well, I don't exactly think Casey likes the fact that I'm here."

"Seriously?"

"Yeps."

"High five!" He help up his hand, and I responded with the usual slap.

"So I see you're here to make your stepsister miserable as well?"

"Uhmm, duh. Why else do you think I'd be at this thing? It's practically a nursing home in here."

"Why? Because everyone here is basically dead?"

"Yeah, pretty much."

"I see, I see," I shook my head. "Good observation."

I glanced over my shoulder, and my heart sunk as I saw Casey approaching. She pipped up from across the kitchen, "Der-ek!"

"What the hell is it now, Spacey?" Derek muttered, just loud enough for her to here.

"Can I maybe speak with you?" She paused. "Alone?"

"Trying to dump me, McDonald?" I inserted, trying to add a bit of humor to the conversation. Derek was the only one that laughed. Casey just folded her arms.

"Please, Derek?" she said, looking pretty mean.

"Whatever." He looked over at me. "I'll be back in a minute?"

"Hmmmm. I don't know if I'll still be here in a minute. Can I have a friendly high five goodbye? Just in case?" I glanced over at Casey. She looked like steam was about to come out of her ears.

"But of course."

* * *

**Mercedes: 1 Casey: 0**

Really bad, I know.


End file.
